1. Field of the Invention
The invention relates to a magnetooptic recording medium for recording and reproducing information by using a laser beam and to a storing apparatus. More particularly, the invention relates to a magnetooptic recording medium for reproducing a recording mark smaller than a laser beam by a magnetically induced super resolution and to a storing apparatus.
2. Description of the Related Arts
In recent years, as an external recording medium of a computer, an optical disk has been highlighted. According to the optical disk, by forming recording pits on the submicron order onto a medium by using a laser beam, a recording capacity can be remarkably increased as compared with that of a floppy disk as a conventional external recording medium. When considering a magnetooptic disk of 3.5 inches, although the initial disk has only a capacity of 128 MB, the disk having a capacity of 1.3 GB has been realized in recent years. A magnetooptic disk of 3.5 inches having the largest capacity of 1.3 GB at present will now be described. High density recording is realized by setting a track pitch to 0.90 μm and setting a mark length to 0.38 μm and, further, by using a super resolution technique called MSR (Magnetically Induced Super Resolution). According to the MSR technique, by devising the medium side, a mark smaller than a spot diameter of the laser beam can be recorded and reproduced. By using the MSR technique, the capacity which is 10 times as large as the capacity of 128 MB of the initial disk can be realized.
The MSR technique will now be described. FIGS. 1A and 1B are diagrams showing a reproducing principle of the MSR technique. As for a medium construction, a 3-layer construction of a recording layer 200, an intermediate layer 202, and a reproducing layer 204 will be described as an example. A mark recorded in the recording layer 200 is influenced in a low temperature portion in front of a laser beam 205 by a reproducing magnetic field, so that a front mask 206 is formed in the erasing direction. An arrow 218 indicates a medium rotating direction. In a portion behind the laser beam 205, heat generated by a reproducing power is accumulated, so that a temperature rises, a magnetization of the intermediate layer 202 is extinguished, and a rear mask 212 which faces a same recording direction 210 as that of a reproducing magnetic field 208 is formed in the reproducing layer 204. An aperture 214 is formed in an intermediate portion between the front mask 206 and rear mask 212. Only in this portion, a magnetization in the recording layer 200 is reflected to the reproducing layer 204 through the intermediate layer 202, so that the reproduction by the MSR is realized. The reproduction of the mark smaller than the laser beam 205 can be realized. The MSR technique is particularly a type called a super resolution (MSR) of the double mask type rear aperture detection system.
In case of reproducing by the MSR, it is necessary to raise the reproducing power to a power larger than that in case of the ordinary reproduction and raise a temperature of the reproducing portion. However, usually, since an ID area between data areas is formed by a pit train, there is no need to raise the reproducing power. If the reproducing power is large, a reproduction signal which is inputted to a reproducing circuit is too large and there is a possibility that it exceeds a dynamic range. It is impossible to make the reproducing power coincide with that of the MSR. Therefore, at the head of the data area where the reproduction of the MSR is executed, since the reproducing power at the time of reproducing the ID area is small, a preheating effect is not obtained and the larger reproducing power is necessary. There is, consequently, a problem such that a reproducing power margin is reduced.
According to the invention, a magnetooptic recording medium and a storing apparatus in which an enough reproducing power margin can be assured even if a reproducing power of an ID area is small are provided.
According to the invention, there is provided a magnetooptic recording medium in which at least a recording layer for recording data and a reproducing layer for reproducing the data recorded in the recording layer are formed on a substrate and the recorded data is reproduced by setting a proper reproducing laser power upon reproduction, wherein magnetizing directions of a buffer area, a sector address area, and a gap area which are sandwiched between data areas where the data is recorded are uniformly magnetized in the recording direction. According to the invention as mentioned above, by uniformly magnetizing the buffer area, sector address area, and gap area which are sandwiched between the data areas in the recording direction, the medium enters a state where an aperture and a rear mask can be formed more easily, so that a medium in which even at the head of the data area without a preheating, the reproduction by the MSR can be realized by a smaller reproducing power, and a reproducing power margin is wider can be provided.
According to the invention, there is provided a magnetooptic recording medium in which at least a recording layer for recording data and a reproducing layer for reproducing the data recorded in the recording layer are formed likewise on a substrate and the data is reproduced by setting a proper reproducing laser power upon reproduction, wherein a portion before a data area where the data is recorded is uniformly magnetized to a recording direction. That is, according to the invention, even if the portion just before the data area is merely uniformly magnetized in the recording direction instead of the whole area of a buffer area, a sector address area, and a gap area which are sandwiched between the data areas, the medium enters a state where an aperture and a rear mask can be formed more easily. A medium in which even at the head of the data area without a preheating, the reproduction by the MSR can be realized by a smaller reproducing power, and a reproducing power margin is wider can be provided.
According to the invention, there is provided a magnetooptic recording medium in which a mark of a recording layer is reflected from an aperture sandwiched between a front mask formed ahead of a reproducing beam in a reproducing layer and a rear mask formed behind the reproducing beam, and data is reproduced by an MSR.
According to the invention, there is provided a magnetooptic recording medium in which a signal is recorded and reproduced onto/from one or both of lands and grooves which are formed alternately on the medium. Particularly, the invention is suitable for the magnetooptic recording medium in which the signal is recorded and reproduced onto/from both of the lands and the grooves.
According to the invention, there is provided a storing apparatus, wherein at least a recording layer for recording data and a reproducing layer for reproducing the data recorded in the recording layer are formed on a substrate of a magnetooptic recording medium, and the storing apparatus comprises: a reproducing unit which reproduces the recorded data by setting a proper reproducing laser power upon reproduction; and a recovery processing unit which, when a predetermined recovery condition such as read error, temperature fluctuation, or the like occurs, uniformly magnetizes magnetizing directions of a buffer area, a sector address area, and a gap area which are sandwiched between data areas in which the data is recorded in the recording direction and, thereafter, retries the reproduction.
According to the invention, there is also provided a storing apparatus, wherein at least a recording layer for recording data and a reproducing layer for reproducing the data recorded in the recording layer are formed on a substrate of a magnetooptic recording medium, and the storing apparatus comprises: a reproducing unit which reproduces the recorded data by setting a proper reproducing laser power upon reproduction; and a recovery processing unit which, when a predetermined recovery condition such as read error, temperature fluctuation, or the like occurs, uniformly magnetizes a portion just before a data area where the data is recorded in the recording direction and, thereafter, retries the reproduction. In the storing apparatus, the reproducing unit reflects a mark in the recording layer from an aperture sandwiched between a front mask formed ahead of a reproducing beam in the reproducing layer and a rear mask formed behind the reproducing beam, and reproduces the data by an MSR. Further, in the storing apparatus, the reproducing unit reproduces a signal recorded on one or both of lands and grooves which are alternately formed on the magnetooptic recording medium.
According to the invention, there is provided a magnetooptic recording medium, wherein a portion of an emboss area or a space area before or after a data area where data is magnetooptically recorded is uniformly magnetized in the recording direction. The emboss areas locating before and after the data area are emboss tins (pit trains) constructed by concave portions formed on the lands in case of the land recording, emboss trains formed with convex portions on the groove so as to have a height up to a land surface in case of the groove recording, or emboss trains of the concave portions or convex portions corresponding to each of the land recording and the groove recording in case of the land/groove recording. All of them are concave and convex emboss trains. The space area is a flat area where no data is recorded, for example, a mirror surface area or a gap area. The position before the data area denotes a range where when the laser beam is located at the boundary of the data area, the portion in this range has to function as a rear mask when it is seen from the boundary.
Further, according to the invention, there is provided a storing apparatus having a format write processing unit which uniformly magnetizes a portion before or after a data area on a magnetooptic recording medium where data is recorded in the recording direction. In a manufacturing line or the like of the magnetooptic recording medium according to the invention, this storing apparatus is used as a format writer of the medium.
The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description with reference to the drawings.